The new rule is intended to aid consumers by keeping fees to a minimum. Experts say low opt-in rates, however, could force banks to change the way they approach fee-based income.

The Center for Responsible Lending surveyed consumers and found the bulk of those responding would not choose to opt in. “They would rather have their debit card transaction declined,” said Leslie Parrish, a senior researcher at the Washington, D.C.-based organization.

Jeffrey Heuer, a partner in the banking and finance practice at law firm Husch Blackwell Sanders in St. Louis, expects an “avalanche of consumer confusion” when the changes take effect July 1. He pointed specifically to the requirement that financial institutions send customers opt-in documents separate from other mailings.

“Customers will do what they did with their deposit agreement and other notices,” he said. “They may file them or more likely throw them away and never really look at them.”

Essentially, Heuer said, consumers will opt out by never opting in.

Bill Ratliff, executive vice president of the Missouri Bankers Association, said that’s what worries him. Will consumers respond?

“Generally when you send something in the mail and ask for a response, you get a 25 percent response if you’re lucky,” he said.

Ratliff said he’s concerned that after the July 1 deadline, banks will experience an influx of irate customers who have been declined at ATMs or retailers.

Low opt-in rates could lead banks to do away with overdraft fees on these types of transactions and look at other alternatives. One option would be overdraft lines of protection, which would essentially turn the overdraft into a loan.

But Parrish said she believes that banks will do their best to get consumer buy-in.

“Banks are gearing up for full-scale marketing campaigns to try to get people to opt in,” she said. “This makes sense because it’s an important revenue source for them.” Parrish said these types of fees account for about 40 percent of the almost $24 billion consumers annually pay in overdraft fees.

“It’s still a pretty substantial source of fee income,” she said, and since most banks have automated systems that sort transactions, making changes to these systems shouldn’t prove to be too expensive or cumbersome.

“Basically you’re turning on or off a software feature for different account holders,” she said. “Any type of fees they’re making off these types of transactions are probably pretty profitable.”

Nationally, some banks have already started preparing for the change. Last fall, Bank of America announced revisions to its overdraft policies, including limiting fees and improving the process for opting out of overdraft protection.

For businesses, Parrish said, the impact of Regulation E should be minimal.

“Even if something is declined, most people have a credit card or cash in their wallet they could use if they really wanted to continue with the purchase,” she said.

Ratliff speculated, though, that retailers may balk at taking a paper check from a customer who has just had a debit card declined, and many people don’t carry much cash on them anymore. “I can foresee some scenarios where people are going to be upset or embarrassed,” he said.